Getting Started

Basic Program Structure

• Package Structure

~  $ tree .
.
└── com
    └── example
        └── Main.java

• Base Java Program

package com.example;

public class Main {
  public static void main(String... args) {
    String greetingMessage = "Hello World";
    greet(greetingMessage);
  }

  private static void greet(String message) {
    System.out.println(message);
  }
}

• Compiling & Running the program

$ javac com/example/Main.java
$ java com/example/Main
Hello World
$

• Entry point to the java application during execution is the main function signature public static void main(String[] args) {...} . JVM looks for this method signature as default.
• JVM - Executes the bytecode generated by the compiler, Makes java code platform-independent
• Bytecode - Compiled output of the javac command which is then in-turm run in JVM
• Read more Details about JDK, JRE & JVM
• How java compilation works ?